Study of U.S. adults finds strong association between higher sodium excretion and higher blood pressure and association between higher potassium excretion and lower blood pressure

What is already known?

The 2015–2020 Dietary Guidelines for AmericansExternal recommend consuming less than 2,300 milligrams (mg) of sodium per day, but the average American’s daily sodium intake is more than 3,400 mg. CDC estimates that 90% of American adults consume too much sodium, and about 29% of U.S. adults have high blood pressure (≥140 mmHg/≥90 mmHg). Studies show that high sodium intake is related to higher blood pressure, while high potassium intake is related to lower blood pressure. The strength of these relationships varies by the type of population assessed and the way sodium intake is measured.

What methods were used?

This study provides a more accurate estimate of the true association of sodium and blood pressure in U.S. adults by:

  • Collecting high-quality 24-hour urine specimens—the gold-standard measure of short-term sodium intake—for the first time in the United States*
  • Estimating usual intake.**
  • Collecting data from 766 adults 20–69 years old in the National Health and Nutrition Examination Survey, a nationally representative survey of the general U.S. population.

What does this article add?

  • There is a strong, direct association between higher sodium excretion and higher blood pressure:
    • People with higher estimated usual sodium intake had higher blood pressure.
    • Systolic blood pressure was 4.58 mmHg higher per 1,000-mg 24-hour sodium excretion.
  • This association was similar for men and women, for people 20–44 and 45–69 years old, and across racial and ethnic groups.
  • People with higher potassium excretion had lower blood pressure.

What are the implications of these findings?

  • When added to the evidence base from longitudinal and interventional studies, these results support lowering sodium intake as part of a healthy dietary pattern, as recommended in the Dietary Guidelines.
  • The findings also support higher consumption of potassium-containing foods and following the Dietary Approaches to Stop Hypertension (DASH)External diet or a similar diet to help lower blood pressure.

Citation

Jackson SL, Cogswell ME, Zhao L, Terry AL, Wang CY, Wright J, et al. Association between urinary sodium and potassium excretion and blood pressure among adults in the United States: National Health and Nutrition Examination Survey, 2014External. Circulation. Epub 2017 Oct 11.

*Why 24-hour urine collection?

  • About 90% of sodium consumed and 77%–90% of potassium consumed is excreted from the body in a 24-hour urine collection.
  • It is unaffected by errors in self-reporting of diet or in nutrient databases.
  • It accounts for sodium and potassium consumed from sources other than food and beverages, such as salt added at the table, salt added during home cooking/preparation, or supplements.

**Why is measuring usual sodium intake important?

  • A person’s intake varies greatly from day to day, because the foods they eat vary.
  • On any given day, a person’s intake may be lower or higher than their average intake over time.
  • These variations can diminish the apparent association of intake with a health outcome.
  • Usual sodium intake accounts for day-to-day variability in a person’s diet. In this study, up to two 24-hour urine collections per person were used with models that account for within-person variability.